Amplifier



Aug. 27, 1940. r R. ORTHUBER El AL 2,212,948

' AMPLIFIER Filed Feb. 26, 1937 2 1 z KIRK/7' L 1 70 LOAD INVENTORS RICHARD ORTHU BER ATTORNEY Patented Aug. 27, 1940 1 UNITED STATES I 2,212,948 AMPLIFIER Richard Orthuber and Eberhard Steudel, Berlin," I

Germany, assignors to Allgemeine 'Elektricitats Gesellschaft, Berlin, Germany, a corporation of I Germany ApplioationFebruarylZfi,1937,SerialNo.127,839

In Germany February 26, 1936 2 Claims. (01. 179-171) The present-invention relates to an amplifier in which a secondary electron multiplier, especially one of thegeneral type disclosed, for example, by Radio Emgineering*for November, 1934, pages 18 and 19,-and an electron tube fed with a carrier wave, are connected in series. the invention the frequency of the multiplier is chosen equal to the frequency of the carrier. This insures the advantage that in both instances the same source of alternating potential may be employed and that interference between the frequencies is avoided.

It is known in the prior art from above mentioned publication that electrons may be amplified or multiplied by virtue of secondary emission. This method may be used for the amplification of electronic currents. Such multiplication is accomplished by impressing an alternating potential between two electrodes which are confined inside an exhausted vessel and, under such conditions, electrons are caused to be accelerated within the tube along reciprocating paths and upon each such impact or bombardment of electrons upon one of these electrodes, secondary electrons are produced. After a certain multiplication, the electrons are then caused to be gathered upon an anode of cylindrical shape and surrounded by the other two electrodes acting as cathodes. For further amplification of the ensuing anode current, an amplifier tube may be connected in the second stage of the electron multiplier.

It is known that under certain circumstances it may be recommendable in the use of an amplifier tube to introduce a carrier wave. In such an instance the said carrier would be modulated by the currents of the multiplier. In such a combination of a multiplier to which an alternating potential is applied, and an amplifier which is impressed with a carrier wave, the inconvenience has been noted that the two frequencies which are used cause mutual disturbance or interference.

It is accordingly an aim and object of the present invention to avoid such disturbing actions by using for the alternating potential of the multiplier and the carrier frequency the same frequency. This step at the same time offers the advantage that the two alternating potentials may be derived from one and the same source of supply. I

The present invention is best described by referring to the drawing, wherein the single figure represents one form of the present invention.

In the drawing, an electron multiplier tube is According to 1 shown at I, which includes a pair of spaced planar cathodes Z', which are capable of emitting a large number of secondary electrons when bombarded by a primary electron stream. Also lo-'- cated within the envelope is an anode 6 which energized by a direct current potential source in order to focus or determine the paths taken by the electrons when accelerated through the tube. The two cathodes are energized by a source of high frequency oscillation which is supplied to the terminals 3 of the primary of a transformer. The secondary 'of the transformer is connected to the cathodes 2 and the mid-point of the secondary is preferably grounded. For collecting the electrons after a predetermined amount of electron multiplication has been performed, the collector anode 6 is maintained positive by means of a source of potential which is connected to the anode by means of the load resistance 9.

A thermionic discharge tube 5 is also included which comp-rises a cathode, control grids I and 4, and an anode. The cathode is connected to ground and the grid 1 is also connected to ground by means of the grid resistance II. The second grid 4 is supplied with the same high frequency oscillations as are applied to the cathodes 2 of the electron multiplier in order that the electron stream of the tube 5 may be modulated at that particular high frequency. The anode of the tube 5 is maintained positive with respect to the cathode by means of an appropriate source of potential, and a load circuit (not shown) is, of course, connected to the anode of the tube.

One of the cathodes of the electron multiplier tube is provided with an aperture through which a stream of electrons or their source of radiant energy may be introduced into the multiplier tube. This stream of electrons preferably is variable in accordance with the signal series to be amplified by the multiplier tube. The stream of electrons is indicated by the arrow A in the drawing. In other cases, the electrons which it is desired to multiply may be liberated within the space itself, an example of this type of operation being where the cathodes themselves are photoelectric and it is desired to use the device as a troduced into the multiplier tube a certain amplification results because of the operation of the multiplier tube, and the amplified signals are then impressed upon the tube 5 which is also modulated by the same frequency as is applied t the cathodes of the multiplier tube. Accordingly, since the same high frequency oscillations are impressed upon both the multiplier tube and the discharge tube 5, no disturbing action results, since both tubes operate at the same high frequency.

Various alterations and modifications may be made in the present invention without departing from the spirit and scope thereof, and it is desired that any and all such modifications be considered within the purview of the present invention, except as limited by the hereinafter appended claims.

Having now described the invention, what is claimed is:

1. An amplifier system comprising an electron multiplier tube including a plurality of spaced planar cathodes, a cylindrical anode substantially surrounding the space intermediate the cathodes, a multi-grid thermionic tube, a source of high frequency alternating current, means for supplying the alternating current from the source to the cathode elements of the multiplier tube and to one of the grids of the thermionic tube, means for applying an input signal to the electron multiplier for amplification thereby, and means for coupling the output of the multiplier to the other grid of the thermionic tube, whereby the alternating current is applied to both the multiplier and the thermionic tube and mutual interference is avoided.

2. The method of amplifying and transmitting energy in which a combination of an electron multiplier device and a thermionic tube is used which comprises the steps of energizing the cathodes of the multiplier tube from a source of a1- ternating current, applying a signal to be amplified to the multiplier tube, supplying the amplified output energy of the multiplier tube to the input of the thermionic tube, and simultaneously modulating the electron stream in the thermionic tube from the same alternating current source whereby mutual interference between the multiplying device and the thermionic tube is avoided.

RICHARD ORTHUBER. EBERHARD STEUDEL. 

